>>9885445That is actually not true, City introduced 6 stud wide minifig cars first.
Mostly they appeared first in the Lego City Undercover Game where every single car was 6 stud wide. 6 stud wide sportscars first appeared in City sets in 2013.
Speed Champions' first set was released in 2015. Speed Champions definetly benefited from the 6 stud design, but its not the reason why City started to favor it. The many various and iconic car designs that it allows are just give more options to build new kind of cars instead of re-relasing the same 4 wide box in a different color.